Vehicle



R. H. KRESS March- 3, 1964 VEHICLE 4 sheets sheet 1 Original Filed Nov.28,1958

RALPH H. KRESS QAFM March 3, 1964 R. H. KRESS 3,123,171

VEHICLE Original Filed Nov. 28, 1958 4 Sheets-Sheet 2 FIG. 3

INVENTOR.

RALPH H. KRESS R. 1-1. KREss March 3, 1964 VEZ-IICLE 4 Sheets-Sheet 3Original Filed Nov. 28, 1958 INVENTOR.

RALPH H. KRESS March 3, 1964 R. H. KRESS 3,123,171

VEHICLE Original Filed Nov. 28. 1958 4 Sheets-Sheet 4 INVENTOR;

RALPH H. KRESS rates i nited This invention relates to vehiclesgenerally, and particularly, the invention relates to ofi-highwayautomotive vehicles. This application is a division of applicationSerial No. 777,070, filed November 28, 1958, now Patent No. 3,614,739,issued December 26, 1961.

Although the advantages of the various aspects of this invention arecapable of application to vehicles generally, they are probably realizedto their fullest extent in automotive vehicles of the oil-highway type.Off-highway vehicles are required to negotiate diiiicult terrain and arene :essarily subject to greater shocks due to unevenness of the terrainencountered by the vehicle. The shocks refer ed to result in tremendousshock loading of the wheel suspension means of such vehicles.

In view of the foregoing, it is one object of this invention to provideWheel drive and suspension means for vehicles which will materiallyreduce unsprung weight and shock loading of the structural elementsinvolved. This and other objects are accomplished in a combination ofwheel drive and suspension devices and mounting means for these devices,in which the devices are of the pistonand-cylinder expansible chambertype. ther objects will be apparent to those skilled in the art from aconsideration of the following description and the appended drawings.

In the drawings:

PEG. 1 is a schematic, largely outline, drawing of a twovehicle trainshowing the location of the wheel suspension means and the couplingmeans by which one vehicle is partially supported on the other.

FIG. 2 is a side elevation view of the tractor final drive housing andexpansible chamber devices, showing the relationship of this combinationof elements to other structural members of the tractor, on a largerscale than FIG. 1.

FlG. 3 is a longitudinal sectional view through one of the expansiblechamber suspension devices, also on a much larger scale than FIG. 1.

FIG. 4 is a view in section substantially on line .4- of FIG. 3.

FIG. 5 is a top plan view, partially schematic, showing the tractorchassis, the wheel suspension devices thereof, and the final drivehousing and its relationship to the wheel suspension devices.

PEG. 6 is a pressure-volume graph showing the difference in principlebetween suspension devices of the type here disclosed and moreconventional types; and

P16. 7 is a view on line i--7 of FIG. 2, but on a larger scale than Fl.2.

Referring now in detail to the figures, FIG. 1 shows a train consistingof a tractor indicated generally at 2 and a trailer 4. The tractorsupports the front end of the trailer by means of a coupling indicatedgenerally at 6 and described in detail in my above-identified Patent3,014,739. The tractor or lead vehicle 2 is provided with Wheels 16 and17; the forward wheels 16 are the dirigible wheels in the embodimentshown, and the wheels 17 are the drive wheels.

The wheels are carried on the vehicle by means of wheel suspensionsindicated generally at 1? and 2% As is explained in detail in my Patent2,914,337, November 24, 1959, each wheel suspension is an eXpansiblechamber device having a cylinder assembly and a piston assembly,

ice

one assembly being connected with the vehicle frame and the other to awheel, the connections for device 2 being shown in FIGS. 24 as ZiU and21L respectively. Thus, in the embodiment shown here, a cylinderassembly 38 and a piston assembly ll make up the expansible chamberdevice Zil (FIG. 3), piston assembly 4% including a piston 42 and apiston rod 44. One of the two assemblies of the expansible chamberdevice is secured to a frame member 45, and the wheel drive housing issecured to the other as sembly. Thus, in the embodiment shown in FIG. 3,the cylinder assembly 38 is secured to frame member 45 by means of asuitable mounting bracket 46, and the wheel drive housing is secured tothe piston assembly Referring now greater detail to FIG. 3, it can beseen that cylinder assembly 38 consists of a cylinder 48 having anintegral closed end 5t? and an open opposite end which is adapted to besealed by a closure 52. Closure is a suitably packed ring and is fixedin tile lower end of cylinder 3% and has sliding engagement with pistonrod The piston assembly and the cylinder assembly together define anannular space 5d, this being the space between the lower face 5'5 ofpiston 42 and the upper surface 5 3 of closure 52 and the bore andpiston rod The closed end 5% of cylinder 48 is provided with a chargingvalve at which may be any one of a number 0 commercially available checkvalves permitting fluid under pressure one direction only and beingeasable to permit id flow in the opposite direction. The above piston ischarged with a dry compressible rluid at a substan al pressure. Bysubstantial is meant several atmospheres. Precisely what the presureneeds to be is a design detail to be worked out by those skilled in theart. it suriices to note here that the pressure must be enough tosupport the load, plus enough to odset the pressure in the opposingchamber below the piston.

In a preferred embodiment of the invention, piston assembly 4-8- ishollow. in the embodiment shown in FIG. 3, this hollow consists of abore 62 in the piston rod 44. Bore 52 is closed at its upper end bypiston 42, and at its lower end by a closure which is here shown aswelded to the surface forming bore 62. The bore 62, closed at its endsas aforesaid, thus provides a reservoir 66. ton 42 is preferabl providedwith a peripheral groove es and wi a plura of circumferentially spacedholes 7%) connecting groove 63 with a cup-shaped reservoir in the uppersurface of piston 42. Piston 42 is here seen as comprising a centralplate portion 72 welded in the up er end of bore 62 (the bore at itsupper end being slightly larger to provide a locating shoulder for plate72), the upper end of piston rod 44, and a ring welded to the outside ofston rod 4 An O-ring 76 is pro- .l in a groove the external surface ofthe aforementioned cup-shaped reservoir is filled w oil as shown at 78,which the groove and lubricates the surface or" engagement on whichpiston 42 slides relative to bore as.

Conduit means are provided to con ect annular space 54 with thereservoir ea. in the emoo -ent shown, suitable piping fil passes throughan opening in plate 72, this opening intersecting a passage 82, in theplate which communicates with annular space 54- through a passage 34 inthat portion of piston rod 4-4 which forms part of piston 42. Piping hitis secured at its lower end in the closure as and communicates with anaxial bore d6 which in turn is intersected by a transverse bore 83. Anysuitable needle valve 9t? may be provided in the lower end of bore whichis suitably threaded for the purpose. A lock nut 92 is preferablyprovided to hold the needle valve 9% in place.

Closure 64 is provided with still another bore which is fitted with aplug 94 to permit charging the reservoir with an incompressible fluidshown at 95. Inasmuch as the preferred embodiment of the invention isintended to employ a combination of a compressible fluid and anincompressible fluid, closure member ti t is fitted with a conduit 98which is long enough to extend at all times above the level ofincompressible fluid in the reservoir 66. At its lower end, conduit 98is fitted with a suitable gas charging valve 16%, similar in principleto the valve 62, discussed above.

As aforesaid, piston assembly 49 is secured to the wheel drive housing,and toward this end, a mounting bracket 192 is secured to closureBracket m2 is suitably apertured to receive a pin iti l; pin Hi4 carriesa ball element I i-9b which cooperates with a socket elem nt Ebb,carried by a mounting ear lib on the wheel drive housing (FIG. 2), toprovide a universal connection of the piston asesmbly with the wheeldrive housing. It will be understood by those skilled in the art thatsimilar means may be used to connect cylinder assembly 33, by means ofbracket 46, to frame member Reference will now be made to FIGS. 2 andfor a discussion in detail of the final drive assembly and itselationship to the rest of the structure. In FIG. 2 the frame member 45and drive wheel 17 are shown in phantom in order not to obscure certaindetails of the invention.

In El-G. 5, any suitable engine or power plant 163 is shownschematically. Any suitable clutch and transmission assembly 262 may beprovided behind the engine. The transmission is shown as having anoutput power connection 164. A drive shaft 166 is connected with theoutput power connection and an input power connection 163 of a finaldrive assembly indicated generally at 17%).

The details of the power train included in the final drive assembly arenot disclosed here because those details are not claimed. It willsufifice to say that the power train of the final dri e assembly may beany suitable train of gears, including some satisfactory differential.The power train is enclosed in a final drive housing 172 which serves asa basic supporting structure for the final drive. As aforesaid, powerinput connection 163 is shown and may be considered a part of the finaldrive assembly. Similarly, power output connections for the final driveassembly are provided, and one of these is shown in FIG. 2 at 174; thereis of course another such power output connection on the opposite sideof the final drive assembly. The drive wheels may be secured to thepower output connection 174 in any suitable manner, as for example bybeing bolted thereto through a suitable number of openings provided forthat purpose, four of which are shown at 1'76 in FIG. 2. It will beunderstood by thos skil ed in the art that suitable brakes may beprovided. Such items are standard and will therefore not be shown here.

The final drive housing is secured to the vehicle frame by a suitableuniversal (ball and socket) type of mounting, here indicated generallyat r73. The fmal drive housing is thus secured to the vemcle frame at apoint closely adjacent to the power input connection 168. As is best eenin FIG. 2, drive shaft res is above the universal connection 178, whichmeans of course that the pivot axis of the final drive assembly is notcoincident with the axis of shaft 156 and connection 1%. This presentsno difficulty because connections 164 and 16% are preferably of theuniversal joint type and are able to accommodate such misalignment ofthe axes of connections i 64 and 163 as will occur due to the offsetrelationship of mounting connection 176.

At its rear end, final drive housing 172 is provided with rearwardlyextending ears, one of which is shown at 11%? in FIG. 2 and is the earlll; referred to above. The two piston-and cyliuder expansible chambersuspension means 2% for the rear wheels are secured between the in carsill} of final drive housing 172 and suitable mounting brackets at theends of frame 45. In order to maintain suitable alignment in a verticalplane as the housing 1'72 swings up and down about the universalmounting 173, some suitable guide means are provided. For example aroller 181R is provided at the rear of final drive housing 172-, theroller to operate in a suitable track 181T.

Operation Reference will be made first to FIG. 3 for a discussion indetail of the operation of the oleopneumatic device there shown. Thepressure chamber defined by bore 6%, upper end 50, and the upper face ofpiston 42 is charged to the desired pressure with a compressible,preferably dry, fluid, as foresaid. A preferred fluid is nitrogen,although of course air can also be used. The pool of oil 7-3 provided inthe top of piston 42 serves the purpose of lubrication as aforesaid. Theannular space 54 is charged with an incompressible fluid, such as oil,and a pool of oil 96 is provided in the reservoir 65. The annular space54 is kept in communication with the pool of oil 78 by means of theconduit 3%. Oil can be added to or taken from the reservoir by removingplug 94. The space above the pool of oil in the reservoir is preferablycharged with the same kind of compressible fluid as is used above thepiston. The pressure of this compressible fluid can be controlledthrough the charging Valve liitl and conduit 93.

As either set of dual wheels 17 strikes a bump in its path, theconnected side of housing 172 moves upward in relation to the frame ofthe tractor. The shock of the sudden upward movement is absorbed bycompression of the compressible fluid in the pressure chamber above thepiston.

In the meantime, it must be remembered that there is a second pressurechamber opposed to the pressure chamber above the piston, this being thepressure cl1am ber formed by the annular space 54-. As piston 42 movesupward, the volume of annular space 54 increases. Cavitation of theincompressible fluid in this space is substantially prevented by theflow of fluid from the reservoir as through passages 8d and 82., andconduit 8%, into the annular space 54. However, even if oil cannot flowthrough these passages quickly enough to prevent cavitation entirely,there is no appreciable interference by such cavitation with the upwardmovement of piston L2. It will of course be recalled that the spaceabove the pool of oil 96 in reservoir as is also charged with fluidunder a substantial pressure. Accordingly, the oil in the pool as tendsto follow the upward movement of piston 42 quite closely.

As the wheel rides oil the bump, the pressure in the chamber above thepiston attempts to restore the piston to its original position. However,as piston 42 begins to move downward in relation to cylinder 43, itencounters the substantially incompressible fluid in the annular space54; piston 42 cannot move downward in cylinder 48 Without displacing oilfrom the space 54 into the reservoir 66 by way of conduit and passages32 and 84. In moving through passages 82 and $4, the oil must flowthrough the variable restriction provided by needle valve 9%. Thus thefact that oil must be displaced from tLB annular chamber or space 54,and the fact that resistance to such movement is olfered both by theneedle valve and the pressure of the gas above the pool %both of theseconditions serve to retard the flow of oil to some extent and give ashock absorber action to the suspension. The rate of flow of oil throughthe conduit all can of course be varied by varying the position ofneedle valve 99.

The action of the suspension when a wheel encounters a hole in its pathis of course similar to the action escribed above when the wheel ridesoff a bump. In this connection, however, it should be remembered thatthe pressure of the compressible fluid in reservoir 66 is desirably suchas to prevent a complete displacement of incompressible fluid or oilfrom the annular chamber 54; in this way, the suspension avoidsmetal-to-metal contact between ie surfaces 56 and 58 in the lower limitsof the stroke of the piston.

For a discussion of another advantage of this invention over moreconventional types of suspension systems, reference will be had to FIG.6. The curve there shown, marked A, is a graphical representation of theequation P V =P V and is of course half of a hyperbole. The ordinatesrepresent pressure and the abscissae represent volume. It will of coursebe evident to those skilled in the art that the perfect relationshipexperienced by curve A does not truly represent the conditions presentin the suspension device disclosed here in that the value P does nottruly represent the stiffness of the suspension device as a whole andthe value V does not truly represent vertical movement of the mountingear 11%) of the wheel drive housing. In other words, even through curveA in FIG. 6 truly represents what happens to the compressible fluidabove piston 42 and above the oil pool 6 to the extent that suchcompressible fluid acts as a perfect gas, curve A cannot be used as isto represent accurately the relationship of vertical displacement(abscissa) against spring stiffness (ordinate). One reason is the factthat the suspension device as a whole utilizes two pressure chamberswhich work in opposition to each other. Even so, curve A serves toillustrate the general principle, which is that, as piston 42 movescloser and closer to the upper limit of its travel in cylinder 48, theresistance to such movement increases asymptotically, and of course thisresistance theoretically approaches infinity as the volume of thecompressible fluid approaches Zero. This relationship is partiallyoffset by the pressure of a compressible fluid in the opposing chamber66.

As a practical result, the suspension device 26 as a whole is a springhaving a variable spring rate rather than a rate which varies linearlyas shown by lines B and C for the vast majority of metallic springs.

The advantages in this area of a suspension device like the one hereindisclosed are readily apparent in considering the characteristics of arelations iip such as is indicated in curve A and compared with thestraight line relationship indicated by B and C. For normal operation ona reasonably smooth road, a soft spring is high- 1y desirable in orderto give the operator a comfortable ride and in order to avoid shakingthe equipment to destruction. A spring having such characteristics isillustrated by the straight line B and by that portion of curve Abetween the points X and Y. On the other hand when the wheels encounterextreme irregularities in the road, it is desirable that the spring bestill near the limits of deflection in order that a small amount ofdisplacemer may encounter a high degree of resistance. This relationshipis indicated by the straight line C and the portion of curve A whichlies between points Q and R. It is thus evident that the combinationhere disclosed and claimed provides suspension means having thecharacteristics of a soft spring for normal operation over a con--paratively smooth road, and a stifi spring for operation on acomparatively rough road.

Referring again to FIGS. 2 and 5, it will be noted that a simultaneousrise and fall of both sides of the final drive housing will effect asimple pivoting of the housing about a longitudinal linear axis throughthe mounting 5 178. More specifically, the longitudinal linear axisthrough mounting 173 lies in the plane of PEG. 2, so that the finaldrive housing pivots in a plane perpendicular to the plane of FIG. 2.However, in the rough terrain which off-highway equipment of this typemust cover, such simultaneous rise and fall of both sides is unusual.The more usual situation is one in which the movement of one side isunrelated to that of the other side, resulting in considerable twistingof the final drive housing 1'72 on its universal joint connection 173with the vehicle frame.

In conventional suspensions, the springs would be so stifi and rigid asto permit very little movement of a wheel 17 relative to the frame,resulting in a very rough ride and necessitating a correspondingslow-down of the vehicle to prevent shaking the equipment to pieces.

To some extent, the hard ride of conventional suspensions is due to thefact that the springs must be still enough to maintain alignment of thedrive train. The suspension devices 20 do not have to maintain alignmentof the final drive assembly, because that is accomplished by the roller181R and the track 181T. In fact, to assure that no sidewise thrust istaken *by the devices 20, they are secured to frame 45 and to housing172 by ball-andsocket connections MU and 21L respectively. Anotherpoint, however, that makes conventional suspensions rather hard ridingis their weight, which, for the same amount of deflection, makes formore unsprung Weight than in suspensions of the type here disclosed.

In view of the foregoing, it will be apparent that this inventionprovides a wheel drive and suspension system which allows for muchgreater deflection and, at the same time, greater rebound and shockcontrol, than conventional suspension devices. Other advantages will beapparent to those skilled in the art.

While there is in this application specifically described one form whichthe invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration and that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claim.

What is claimed is:

Drive mechanism for an automotive vehicle having a frame, a final drivehousing, a universal joint securing the housing to .the frame at onepoint, a pair of drive wheels rotata-bly carried by the housing in alaterally spaced relationship, a pair of laterally spacedpiston-and-cylinder suspension means, each suspension means havingintegral rebound control means comprising a load supporting chambercharged with a compressible fluid, an opposing chamber charged with anincompressible fluid, a third chamber associated with the piston, andpassage means permitting fluid flow between the second and thirdchambers, universal joints securing the suspension means to the frameand to the housing, and means on said housing and frame to maintainlongitudinal alignment of the housing independently of the suspensionmeans and including a roller element and a track element, one elementbeing on said housing.

References Cited in the file of this patent UNITED STATES PATENTS2,340,149 Slack Ian. 25, 1944 2,738,024 Saives Mar. 13, 1956 2,914,337Kress Nov. 24, 1959

